Error CS1001: identifier expected

First off, indent your code properly:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Paddle : MonoBehaviour
{
    public bool isPlayer1;
    public float speed;
    public rigidbody2D rb;
    
    private float movement;
    // Update is called once per frame
    void Update()
    {
        {
            if (isPlayer1)
            {
                movement = Input.GetAxisRaw("Vertical");
            }
        }
        movement = Input.GetAxisRaw("Vertical2");
    }
    rb.velocity = new Vector2(rb.velocity.x, movement * speed);
}

It makes it a lot clearer to see what is actually happening!
And the first thing that is obvious is that there is a pair of redundant curly brackets in there:

    void Update()
    {
        if (isPlayer1)
        {
            movement = Input.GetAxisRaw("Vertical");
        }
    movement = Input.GetAxisRaw("Vertical2");
    }

The second thing that becomes obvious is that this line of code:

rb.velocity = new Vector2(rb.velocity.x, movement * speed);

Isn't inside any method.

That won't compile: you cannot execute code unless it is inside a method - there is no way to call it!

So start out by working out where that code should be, and your problems may start to go away...